Human warts (verrucae vulgaris) are benign, cutaneous neoplasms induced by an oncogenic DNA virus closely related to SV40 and polyoma viruses. Little is known about the biology of human warts, but in preliminary experiments antigens were detected and partially purified from the nuclei and cell surfaces of wart tissues. The antigens are detectable by immunofluorescence in wart tissue and several types of squamous cell carcinomas but not normal skin or basal cell carcinomas. Experiments are designed to further purify these antigens, develop a tissue culture model of the viral wart, correlate host immunological responses to wart antigens with the clinical course of the neoplasms and compare the wart antigens to known tumor and cellular antigens. These studies provide an opportunity to determine the chemical nature of virus-associated human tissue antigens and evaluate their role in humoral and cellular host responses.